.box {
    width: 100px;
    height: 100px;
    background: #f5f5f5 url("../images/upload.png") no-repeat center center;
    background-size: cover;
    border: 1px dashed #ccc;
}

input {
    width: 100%;
    height: 100%;
    opacity: 0;
}
button {
    display: inline-block;
    width: 100px;
}